Body Fat Calculator

Written by Great Medico

Updated September 24, 2026 •2 min read

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A tape measure or scale can produce plenty of numbers; the useful part is knowing what relationship you are actually looking at. Body Fat Calculator keeps that question narrow and visible.

What this calculator does

Body-fat percentage can describe body composition more directly than body weight alone. This calculator offers three built-in estimation routes and also reports estimated fat mass, lean mass, and BMI. Anthropometric equations are convenient because they use simple measurements, but they describe body size or proportion rather than directly measuring tissue composition or health.

How to use it

Select the body-fat method first. Enter age, sex, height, and weight for the ADA or BMI-based paths; if you choose the U.S. Navy method, add the circumference fields that appear for that sex. Keep tape measurements in the supported units and measure at consistent anatomical landmarks.

How the calculation works

Choose the American Diabetes Association, U.S. Navy, or BMI method. The ADA path uses age, sex, and BMI; the Navy path uses sex-specific circumference equations with height, neck, waist, and—when applicable—hip measurements; the BMI path estimates body fat from BMI, age, and sex.

Example

For the sample values prefilled in this calculator, the primary result is 21.97 % (Estimated body fat), Body fat weight is 16.48 kg, and Lean body mass is 58.52 kg. This example is there to show how the inputs flow through the implemented equation; replace the sample values with your own measurements before using the result.

How to interpret the result

Treat the percentage as an estimate. The accompanying fat-mass and lean-mass values simply divide the entered body weight according to the estimated percentage, while BMI provides a separate weight-for-height context.

Limitations and notes

Circumference and equation-based methods can differ meaningfully from DXA or other direct body-composition assessments. Results depend on the selected method and measurement quality, so comparisons are most useful when the same method and technique are repeated.